The present invention is directed to the electrical testing of electronic packaging and, more particularly, is directed to an apparatus and method for the non-contact electrical test of electronic packaging using ionization under standard atmospheric conditions.
As modules and board geometry get smaller with increasing demands for high volume testing in a cost competitive manner there is a need to have a test applicable to fine geometries while remaining fast, inexpensive and practical in a high volume manufacturing environment.
One significant class of nets to test in the area of electronic cards and modules are conductive nets from one side of the module to the other. An open or shorting defect in these nets would be a yield detractor. Even if a circuit is not a dead open, if it violates a minimum conductive area criteria there could be reliability or other yield related problems. Each side of the electronic package has features and will be used to attach in some manner to some other electronic package. One side of an electronic module or board will usually attach to a finer geometric ground rule device such as a semiconductor chip. This side is typically referred to as the top side metallurgy (TSM). The other side will usually attach to a coarse geometry ground rule device such as a board, back plane or other packaging module.
Due to the small geometries of the TSM it may not be desirable from a handling point of view to mechanically probe the top for some or all electrical test purposes. Similarly, due to the small geometries of the TSM it may not be practical or even possible to mechanically probe the TSM. The opposite side, typically referred to as the bottom surface metallurgy (BSM), has a coarser geometry and larger pads. The BSM is therefore more practical to mechanically contact for test purposes. Nets connecting the TSM features to the BSM features are critical to the operation of the device and requires test to assure functionality. The present invention includes the use of an ionization source, a mechanical fixture and an array of weak current sensing analog electronics. The same apparatus can be used to test both opens and shorts. The method does not contact the features on one side of the device under test.
Accordingly, it is a purpose of the present invention to provide a method for the non-contact electrical test of opens.
It is another purpose of the present invention to provide a method for the non-contact electrical test of shorts.
It is another purpose of the present invention to provide to an apparatus for the non-contact electrical test of electronic packaging using ionization under standard atmospheric conditions.
These and other purposes of the present invention will become more apparent after referring to the following description considered in conjunction with the accompanying drawings.